This invention relates to air flow within internal combustion engines, including but not limited to mixing recirculated exhaust gas recirculation with intake air in internal combustion engines.
Internal combustion engines are known to include exhaust gas recirculation (EGR) systems to reduce NOx (nitrous oxide) emissions. Air enters the engine through a turbocharger through a compressor, which pressurizes the air. The pressurized air flows to an intake manifold and enters the cylinders of the engine. The compressor is coupled to a turbine, which is driven by exhaust gas from the cylinders. The exhaust gas from the cylinders enters an exhaust manifold and flows into the turbine. The exhaust gas exits the turbine and is vented to the atmosphere. A fraction of the exhaust gas is diverted from entering the turbine and routed back to the intake manifold in a process known as exhaust gas recirculation (EGR). The resultant air charge to the cylinder contains both fresh air and combusted exhaust gas.
The EGR flow is driven from the exhaust manifold and is mixed with the air from the compressor to provide the air charge to the cylinders. The mixing process may need to take place in a short path, thus preventing a good mix of the EGR flow with the compressed air. Further, the EGR flow may be partially prevented from entering the passage with the compressed air because the compressed air flow is at the same or higher pressure than the EGR flow. As a result, the EGR flow may not successfully reach the cylinders as desired.
Accordingly, there is a need for a better way to mix EGR flow with air prior to introducing the mixture into the cylinders.
An apparatus for improving flow mix includes an EGR passage having an EGR flow moving through the EGR passage and into a mixing passage. An engine intake air passage has a first end and an engine intake air flow moving through the engine intake air passage and into the mixing passage. The exhaust gas recirculation passage, the mixing passage, and the engine intake air passage form a junction. An obstruction is positioned engine intake air flow such that a part of the engine intake air flow is disrupted while entering the mixing passage while permitting the EGR flow to enter the mixing passage and mix with the air flow.